We recently upgraded our CRM instance from 2011 to 2016 on-premise. All GUIDs, schema, etc. remained the same.

When we re-synced Marketo to MSD, we got 1000s of errors, all the same:

-2147220685 A record was not created or updated because a duplicate of the current record already exists.

The company that administered the CRM upgrade added a bunch of new/stock duping rules in MSD. By unpublishing all the dupe rules -- not something we want to leave in place, of course -- the dupe issues were fixed. Here are our 14 rules:

My question: We're going to look back at our 2011 instance to see what we had in place -- when everything was working -- but would love to see how the community rolls here. If anyone is willing to share a screen shot or two, that'd be fantastic. We were thinking of creating some rules around "lead source: marketo."

Interested in following this thread, as this is a common error that we get with Dynamics 2011. We saw some improvement when we upgraded our Marketo Sync Connector, but we do still have some errors that pop up with this message.

As an FYI, you likely had 1000s of duplicates in the past, when Marketo tries to write a value, the error is generated. For example, I know I have thousands of dupes in my database, but I am only presented with errors around 10-15 per day; only as someone creates the duplicate in CRM, or there is a write error.

When your system was resynced, many writing actions were taking place, hence why all the errors appeared.

A number of our dupes come from team members adding contacts to their phone via Outlook, which then syncs them back into CRM, horrible system I know, we're working to alter this particular process. We have another third party tool that is integrated with CRM that also generates dupes, simply due to the fact that the tool is limited in its abilities with CRM vs SF.

Good points here, Jonathan. I'm constantly demanding that we need to improve our overall governance in CRM. Below is a slide I always include in my standard PPT deck that talks to the Marketo/CRM integration and data integrity challenges we have in our environment. The "out-of-the-box" capabilities - like the Outlook plug-in and mobile CRM - is most disruptive.